1. Field of the Invention
The present invention relates to a template and process for drilling multiple subterranean wells from a single vertical or deviated cased well bore and for completing such wells via separate casings positioned within the well bore, and more particularly, to a template and process for drilling and completing such multiple wells which will permit remedial operations to be conducted in one well while fluid, such as hydrocarbons, are simultaneously being produced from a subterranean formation and/or fluid is simultaneously being injected into the subterranean formation via the other well(s).
2. Description of Related Art
Increasingly, well bores are being drilled into subterranean formations at an orientation which is purposely deviated from true vertical by means of conventional whipstock technology or a mud motor secured in the drill string adjacent the drill bit. In fractured subterranean formations, deviated wells are utilized to increase the area of drainage defined by the well within the subterranean formation, and thus, increase production of hydrocarbons from the subterranean formation. An inherent problem in utilizing a conventional whipstock to drill a deviated well is that both the depth and radial orientation of the whipstock is set when the whipstock is positioned in the well bore and cannot be changed without retrieving the whipstock from the well bore and changing the depth and/or radial orientation thereof.
In addition, wells drilled from offshore drilling platforms are usually deviated to increase the number of wells which can be drilled and completed from a single platform. Offshore drilling platforms which are utilized in deep water to drill and complete wells in a subterranean formation vary in size, structure, and cost depending upon the water depth and the loads in which the platform will be set. For example, a platform may be constructed to be supported in part by one leg or caisson which extends to the ocean floor or by as many as eight such legs or caissons. Costs of such offshore drilling platforms vary from approximately $5,000,000 to $500,000,000. Each offshore drilling platform is equipped with a set number of slots via which deviated wells can be drilled and completed through surface casing which is secured at the mudline by conventional techniques. Due to the significant capital expenditure required for these offshore platforms, a need exists for a template and process for drilling and completing multiple cased wells via a single surface or intermediate casing.
Accordingly, it is an object of the present invention to provide a template and process for drilling and completing multiple wells within a subterranean formation via a single surface or intermediate casing and for completing such multiple wells via separate casings positioned through the surface or intermediate casing.
It is another object of the present invention to complete such multiple, cased wells in a manner such that remedial operations can be conducted on one well while hydrocarbons from the subterranean formation are simultaneously being produced from the other wells which are completed via separate casings positioned within the same surface or intermediate casing.
It is a further object of the present invention to provide a template and process for drilling multiple cased wells from a single surface or intermediate casing without the use of a whipstock.
It is a still further object of the present invention to provide such a template for drilling multiple cased wells from a single surface or intermediate casing which is relatively simple in construction, which permits casing of each multiple well to separately depend from the template, and which provides that the separate casing of each multiple well extend to the surface.